Floatation type rust preventive



United States Patent FLOATATION RUST PREVENTIVE No Drawing. Application May 14,1957 Serial No. 658,964

3 Claims. (Cl. 106-14) This invention is concerned with a floatation type rust preventive useful for inhibiting corrosion of ballast tanks, coifer-dams, and the like. More specifically, this invention proposes a rust preventive composition comprising, besides a distillate petroleum oil, minor amounts of a substituted imidazoline wetting agent and a rust inhibitor combination.

Floatation type rust preventives are applied to metal surfaces by floating the composition on. the surface of water and then raising and lowering the water level, whereby a protective film is deposited on the metal surface that is in contact with the water. It is necessary that a protective film laid down on a metal surface in this manner be very tenacious, and be resistant to removal by further contact with water.

The present invention proposes a composition that satisfies these requirements of a floatation type rust preventive and that leaves a very tenacious water-displacing film on metal surfaces. With this rust preventive composition, a surprising reduction in the corrosition rate of the metal surface is obtained.

The composition of this invention comprises a heavy distillate petroleum oil as a base, a select wetting agent, and a select combination of rust inhibitors. It has a flash point above 335 F., a pour point below 15 F., and a gravity below 225 API so that it is ideally suited for its intended use.

More specifically, the composition of this invention comprises:

Weight percent Heavy distillate oil 97.7-94.3

The heavy distillate oil can be an untreated or treated distillate having a viscosity at 210 F. in the range of 50 to 100 SSU, a viscosity index in the range of 20 to 100, a boiling point in the range of 350 F. to 750 F. at mm. mercury pressure, and an API gravity of 22.5 to 17.5". Such distillates can be readily separated from crudes or similar materials by simple distillation, and the distillate so obtained can be further treated, if desired, as by sulfuricacid, phenol extraction or clay filtration treatments. Preferred distillates are those obtained from naphthenic crudes, although distillates from Mid-Continent or paraffinic crudes can also be employed.

{The selected substituted imidazoline used has the following formula:

R is an unsaturated straight chain alkylene radical selected to have in the range of 16 through 20 carbon atoms. It is necessary to use a straight chain radical because compounds of this structure are the ones most eifectively adsorbed upon metal surfaces and provide a maximum degree of protection. It is necessary that the alkylene radical be unsaturated to provide adequate oil solubility. It is necessary that the alkylene radical contain 16 through 20 carbon atoms because when the chain radical is shorter, the protection given by the compound is not s-utficient, and when it is longer the wax like nature of the compound gives it poor oil solubility.

R is an alkyl radical containing either 2 or 3 carbon atoms. The imidazoline can be synthesized from either aminoethyl ethanol amine or amino ethyl propanol amine. The terminal hydroxy group is necessary to insure proper water solubility of the imidazoline.

Suitable imidazolines can be made by reacting about 1 mole of oleic or similar acid with 1 mole of amino ethyl alkanol amine at an elevated temperature. Upon the elimination of two moles of water a substituted imidazoline is formed. The Water can be conveniently removed by azeotropic distillation with a solvent such as xylene. In a typical preparation, employing xylene in the reaction mixture and a reaction temperature of about 300 F., the imidazoline is recovered in nearly theoretical yields.

The unsaturated fatty acid in the above composition is unsaturated and contains 16 through 20 carbon atoms per molecule. Examples of suitable fatty acids are oleic acid, hexadecenoic acid, gadoleic acid, palmitoleic acid and linoleic acid.

The metal sulfonate is one selected from the group consisting of calcium and barium sulfonates, known to the art, and has an average molecular Weight in the range of 800 to 1000. The metal sulfonates can be either basic or neutral. Typical analyses of the sulfonates are shown below.

Barium sulfonate (basic):

Barium 16.0 wt. percent.

Sulfur 2.64.

Neutralization number 65.3 basic.

Molecular weight 912.

Soap 41.3 Wt. percent. Calcium sulfonate (neutral):

Calcium 2.0 wt. percent.

Neutralization number 2.1 basic.

Molecular weight 870.

Soap 29.2 wt. percent.

The sulfonic acids used in forming the sulfonates can be those derived from petroleum or from synthetic alkyl aromatics. Suitable sulfonates can be obtained by treatment of a lubricating oil fraction or an alkyl aromatic with fuming sulfuric acid in a conventional manner. Synthetic sulfonic acids can also be used; for example, polypropyl benzene sulfonic acids; didodecyl toluene sulfonic acids; octadecyl naphthylene sulfonic acids; polypropyl naphthylene sulfonic acids; and the like are useful.

Preferred sulfonates are synthetic sulfonates derived from alkylated benzenes with the alkyl radicals thereof having 17 through 27 carbon atoms per molecule.

The sulfonates can be prepared from the sulfonic acid by simple neutralization with a basic compound of the metal, e.g., the oxide or hydroxide can be used. Alternately the sulfonates can be prepared by double decomposition of sodium sulfonate with a salt of barium or calcium as is well known in the art. To obtain the desired molecular weight sulfonate from a mixture distillation or solvent extraction can be employed.

Example.Two compositions were made up as shown in Table I.

The oil was obtained from a naphthenic crude. It was an untreated distillate and had the following inspections:

Viscosity, SSU at 210 F. L 61.8 Viscosity index 29 Four point, F. Flash point, P. 410

Gravity, 'API' 21.8

The barium sulfonate was a 41.3 wt. percent concentrate in a petroleum neutral. It was obtained by a process involving the sulfonation of the bottoms from the alkylation of benzene with tetrapropylene. The bottoms comprising C C alkylated benzene was treated with oleum and the sulfonic acid thus obtained reacted with barium oxide. The metal sulfonate had an average molecular weight of 912, a barium content of 16.0 wt. percent and a basic neutralization number of 65.3.

The protective properties of the composition were evaluated by means of a simulated ballast tank exposure test. In. this test, six pre-rusted steel panels were subjected' to cyclic immersion in synthetic sea water, covered by a layer of the corrosion preventive, for a period of 12 weeks. Six pre-rusted control panels were subjected to the same cycle using only sea water. The corrosion rate, in inches penetration per-year, was calculated from the weight: loss during the test. The test procedure was as follows:

(a) Six pre-rusted panels were suspended in a large tank by means of glass hooks.

(b) The test panels were wetted by filling the tank from a reservoir with synthetic sea water. The panels were left covered for one minute and the level of the water was then lowered to expose the test panels.

(c) The corrosion preventive was placed on top of the water layer. The storage tank had a diameter of about 12 inches. The amount of corrosion preventive added was 400 cc., which gave a film of oil about 1% inches thick on the water surface.

(d) The test panels were immersed and coated by running water into the tank from the reservoir. The immersed panels were allowed to standfor one minute, and then the water was withdrawn to expose the panels. This step was then repeated.

(e) The tank was filled to completely immerse the panels and left for seven days.

(1) At the end of seven days, the water level was loweredv to expose the test panels.

(g) Air was bubbled. through the tank when the water level was down at a rate of 2.0-2.5 cubic. feet per hour for seven days.

(.h) Steps (e), (f) and (g) were repeated until a total exposure period of 12 weeks was completed.

(i) After the 12 week exposure period, the panels were removed from the tank, cleaned of oil, derusted, and the weight loss measured. The corrosion rate was then calculated in terms of inches per year penetration.

The control panels, in the absence of a corrosion preventive, gave a corrosion rate of 0.0115 inch per year. Composition A gave a rate of 0.0025 inch per year, and the composition of this invention, composition B, gave a rate of only 0.0001 inch per year. Thus, it can be seen that as compared to-the control, composition A gave a 78% reduction in the corrosion rate while the composi tion of this invention gave an unexpectedly large decrease of 99% in the corrosion rate.

Having described this invention, what is sought to be protected by Letters Patent is succinctly set forth in the following claims.

What is claimed is:

1. A floatation type of rust preventive having a flash point above 335 F., a pour point below 15 F., and a specific. gravity below 22.5, consisting essentially of: 97.7 to 94.3. wt. percent of a heavy petroleum distillate having a viscosity at 210 F. in the range of 50 to 100 SSU, a viscosity index in the range of to- 100, a boiling point in the range of 350 F1 to 750 F at 10 mm. mercury,

and. anAPI: gravity in the range of 22.5 to 17.5; 1 to 2 weight percent of a sulfonate selected from the group consisting. of calcium and barium sulfonates' having an average molecular weight in the range of 800 to 1000; 0.3 to. 0.7 wt. percent of an. unsaturated straight chain fatty acidhaving in the range of 16 through 20' carbon atoms per molecule; and 1 to 3' wt. percent of a substituted i'midazoli'ne having the following formula:

N-OH,

cal' having in the range of 16 through 20 carbon atoms and R is an alkyl radical containing in the range of 2 to 3 carbon atoms.

2. The rust preventive of claim 1 wherein said sulfo mate is a basic sulfonate derived from an alkylated benzene, the alkyl radicals thereof having in the range of 17 through 27 carbon atoms per molecule.

3. A floatation type of rust preventive having a flash point of about 410 F., a pour point of about 5 F.,

and an API gravity of 21.0, consisting essentially of 94.5 wtpercent of a petroleum distillate having a viscosity at 21'0" F. of 61.8 SSU, a viscosity indexof 29, and an API gravity of 21.8"; 3.0 wt. percent of a concentrate containing about 41.3 wt. percent of a barium salt of an alkyl aryl 'sulfonic acid having an average molecular weight of 912; 05% of oleic acid and 2 wt. percent of 1-(2-hydroxyethyl)-2 heptadecenylimidazoline.

References Cited in the file of this patent UNITED STATES PATENTS 2,466,517 Blair et -al'-. -1. Apr. 5, 1949 2,739,126 Benbury et a1 Mar. 20, 1956 2,811,489 Laug Oct. 29, 1957 

1. A FLOATATION TYPE OF RUST PREVENTIVE HAVING A FLASH POINT ABOVE 335*F., A POUR POINT BELOW 15* F., AND A SPECIFIC GRAVITY BELOW 22.5, CONSISTING ESSENTIALLY OF: 97.7 TO 94.3 WT. PERCENT OF A HEAVY PETROLEUM DISTILLATE HAVING A VISCOSITY AT 210*F. IN THE RANGE OF 50 TO 100 SSU A VI SCOSSITY INDEX IN THE RANGE OF 20 TO 100, A BOILING POINT IN THE RANGE OF 350*F. TO 750*F. AT 10MM. MERCURY AND AN API GRAVITY IN THE RANGE OF 22.5 TO 17.5; 1 TO 2 WEIGHT PERCENT OF A SULFONATE SELECTED FROM THE GROUP CONSISTING OF CALCIUM AND BARIUM SULFONATES HAVING AN AVERAGE MOLECULAR WEIGHT IN THE RANGE OF 800 TO 1000; 0.3 TO 0.7 WT. PERCENT OF AN UNSATURATED STRAIGHT CHAIN FATTY ACID HAVING IN THE RANGE OF 16 THROUGH 20 CARBON ATOMS PER MOLECULE; AND 1 TO 3 WT PERCENT OF A SUBSTITUTED INIDAZOLINE HAVING THE FOLLOEING FORMULA: 